Ruthenium Loaded On Ferro-bimetallic Oxides Catalyze The Oxidation Of 5-hydroxymethylfurfural To 2,5-furandicarboxylic Acid

With the depletion of the world’s fossil resources,the development and use of new energy and renewable resources is imminent.Biomass resources,as a renewable resource,have the characteristics of abundant stocks,widespread sources and biodegradability.5-hydroxymethylfurfural（HMF）is a potential biomass platform compound,and 2,5-furandicarboxylic acid（FDCA）,one of the many chemicals further derived from HMF,can be used as an alternative to petroleum-based terephthalic acid in the production of polyester chemicals.FDCA is also an important intermediate in biopolymers,fine chemicals and pharmaceuticals.It is of great importance to develop a catalytic system with high activity and stability to achieve the selective oxidation of HMF to FDCA.Ferro-bimetallic oxides have attracted the attention of researchers in recent years because of their magnetic properties,which make it easier to separate the catalyst from the product.In order to further improve the catalytic activity of ferro-bimetallic oxides on the selective oxidation of HMF,a relatively inexpensive Ru loaded on ferro-bimetallic oxides as catalysts,and studied their catalytic performance in the selective oxidation reaction of HMF,and a series of characterization methods were used to characterize the catalysts.The main research work of this thesis was as follows:（1）Cr-Fe bimetallic oxides with various Cr/Fe molar ratios were prepared and used as carriers to load Ru nanoparticles in order to prepare the catalysts.X-ray diffraction（XRD）,N₂adsorption-desorption experiments,transmission electron microscope（TEM）,energy dispersive spectroscopy（EDS）,NH₃-programmed temperature desorption（NH₃-TPD）,H₂-temperature programmed reduction（H₂-TPR）,X-ray photoelectron spectroscopy（XPS）and inductively coupled plasma optical emission spectrometer（ICP-OES）were used to characterize the catalyst.The amount of Ru loading,alkali amount,reaction temperature,reaction time,O₂pressure and catalyst amount were optimized.For the selective oxidation of HMF,the bimetallic oxide carrying 4 wt%Ru and a Cr/Fe molar ratio of 2/1 demonstrated the highest catalytic activity.After optimizing the reaction conditions,0.06 g KHCO₃was added,the oxidant O₂pressure was1 MPa,the reaction temperature was 100°C,0.1 g Ru/Cr2-Fe1-O catalyst was used and reacted in aqueous solution for 16 h,HMF was completely converted and the yield of FDCA reached99.9%.The excellent catalytic activity of 4 wt%Ru/Cr2-Fe1-O could be attributed to strong low-temperature reduction ability,more weak acid centers and abundant oxygen species.Through experiments,a potential reaction mechanism for the HMF oxidation reaction over 4 wt%Ru/Cr2-Fe1-O was proposed,Ru⁰is the active center of the catalyst.The catalyst was not significantly inactivated after repeated use for 5 times,and the active component Ru did not leach out,and the moderately strong interaction between Ru and Cr2-Fe1-O helped to improve the stability of the catalyst.（2）The magnetic nickel-iron spinel carrier NiFe₂O₄was prepared and used as carrier supported Ru nanoparticles to prepare Ru/Ni Fe₂O₄catalyst.XRD,N₂adsorption-desorption experiments,EDS,NH₃-TPD,H₂-TPR,XPS and ICP-OES tests were used to characterize the catalysts.Alkali amount,reaction temperature,reaction time,O₂pressure and catalyst amount were optimized.The results showed that the surface oxygen species of the Ru/Ni Fe₂O₄catalyst were abundant,and compared with the carrier,the specific surface area and surface acid content of the catalyst increased after Ru loading,and there was an interaction between Ru and the carrier,which may be the key to the high activity and stability of the catalyst.The catalyst was used for the selective oxidation of HMF,and the experimental results showed that the catalytic activity of the catalyst was significantly increased after loading Ru.After optimizing the reaction conditions,after adding 0.08 g of KHCO₃,the oxidant O₂pressure was 1 MPa,the reaction temperature was 80°C,0.1 g of Ru/Ni Fe₂O₄catalyst was used to react in aqueous solution for 12h,HMF could be completely converted,and the yield of FDCA was 98.1%.Through experiments,a possible reaction mechanism of HMF oxidation on Ru/Ni Fe₂O₄was proposed.Ru/Ni Fe₂O₄retained high activity after 5 cycles,the active component Ru was not easily leached from the support and the catalyst was magnetic to facilitate separation from the reaction solution.（3）Magnetic cobalt iron spinel carrier CoFe₂O₄was prepared and used as carrier loaded Ru nanoparticles to prepare Ru/Co Fe₂O₄catalyst.XRD,N₂adsorption-desorption experiments,EDS,NH₃-TPD,H₂-TPR,XPS and ICP-OES tests were used to characterize the catalysts.Alkali amount,reaction temperature,reaction time,O₂pressure and catalyst amount were optimized.The results showed that the total proportion of lattice oxygen and surface oxygen of Ru/Co Fe₂O₄was relatively large,which was conducive to promoting the oxidation reaction.Compared with the carrier,the low temperature reduction capacity of the catalyst increased after Ru loading,and the acid content on the catalyst surface increased.The catalyst was used for the selective oxidation of HMF,and the experimental results showed that the catalytic activity of the catalyst was significantly increased after Ru loading.After optimizing the reaction conditions,0.06 g KHCO₃was added,the oxidant O₂pressure was 1 MPa,the reaction temperature was 90°C,0.1g Ru/Co Fe₂O₄catalyst was used,and the reaction was carried out in aqueous solution for 12 h,HMF was completely converted,and the FDCA yield reached 99.0%.Through experiments,a possible reaction mechanism of HMF oxidation on Ru/Co Fe₂O₄was proposed.After repeated use for 5 times,no obvious inactivation of the catalyst occurred and no leaching of the active component Ru was found.Ru/Co Fe₂O₄was also magnetic,and the catalyst could be directly separated from the reaction liquid using an external magnet.